Late Roman Unit Sizes

[Frank]

I guess, one problem is, that many ancient authors are not talking about paper strength. If somebody reports 12.000 soldiers from 5 legions, this just means, that these 6 legions had in average a strength at this point of time of 2400 men. Perhaps one was 5000 men strong but others just 1000, but the author was too lazy to mention that these 1000 men were just a vexillatio of 2 cohorts. We also know from some morning reports, that 50% strength was not unusual. So I am not surprised, if a 5000 men strong legion appeared with just 2500 on the battlefield.

So imho it makes not that much sense to calculate paper-strength based on battle reports which use probably current strength.

Nevertheless, there are a lot of good arguments, that units in late empire became smaller. Also the legion. It also seems that the legion lost its role as organizational main unit. It was never a tactical or a strategic unit, but an organizational one. The tactical unit was the vexillatio or the cohort and the strategic the exercitus. It became just another tactical unit of perhaps cohort millaria size